Generally, an electromagnetic wave refers to a wave in which an electric field and a magnetic field propagate across space while forming a right angle and changing periodically. It is well known that electromagnetic waves are being more widely used due to the development of electrical and electronic engineering.
Furthermore, today, office devices, such as a television set, a computer monitor, etc. are widely used at homes or offices. In particular, in winter, electric heating devices, such as an electric pad, an electric mat, an electric blanket, and an electric stove, are widely used. Moreover, when a user is exposed to the electromagnetic waves of a home appliance, such as an electric bed, an microwave oven, a washing machine, a refrigerator or an electric rice cooker, an office device, an industrial device, or the like, probability that the user has a disease, such as headache, increases, and also there are a lot of disadvantages.
Accordingly, various materials have been developed to absorb and block/remove such electromagnetic waves. As conventional art proposed to develop such materials, there are being applied various schemes, including a scheme in which: rubber having the functions of absorbing and blocking/removing electromagnetic waves is manufactured through injection or extrusion molding after adding ferrite, i.e., an electromagnetic wave blocking/removing material, to a rubber composition, i.e., an insulating material, in the form of powder or chips, or a mat having the functions of absorbing and blocking/removing electromagnetic waves is manufactured through extrusion molding after mixing a particulate electromagnetic wave absorbing agent and a particulate conductive material with any one of rubber and thermoplastic resin; and the rubber or mat is attached to a product which generates electromagnetic waves.
However, the products manufactured using the above schemes are formed by mixing compositions having different specific gravities with each other. In this case, unless the compositions are sufficiently mixed with each other, it is difficult to uniformly distribute the electromagnetic absorbing agent and the conductive material due to the difference between the specific gravities of the compositions. Accordingly, a problem arises in that the functions of absorbing and blocking/removing electromagnetic waves are not uniformly performed.
As a prior art document related to the present invention, there is Korean Utility Model Registration Application Publication No. 20-1998-010576 (May 15, 1998).